As functional elements in the electric/electronic field or the optical field, there is known an electroluminescent element capable of emitting light by applying a voltage. In general, this electroluminescent element can be broadly classified into an inorganic electroluminescent element having a light-emitting layer which contains an inorganic electroluminescent material (hereinafter referred to as “inorganic EL element”) and an organic electroluminescent element having a light-emitting layer which contains an organic electroluminescent material (hereinafter referred to as “organic EL element”).
In comparison with the organic EL device, the inorganic EL device is hard to emit light with high luminance, it has such an advantage that not only it is excellent in long-term stability, but it stably causes light emission even under a severe condition such as a high temperature. For that reason, in order to utilize it in fields where weather resistance, heat resistance, long-term stability, or the like is required, studies regarding the inorganic EL element are being continued.
An inorganic EL element which is driven by an alternating current source can be formed on paper or a polymer film by utilizing a printing technology, and it forms a market as an illumination device in which flexibility is required. As such an inorganic EL element, there is known an electroluminescent element in which an insulating layer and a light-emitting layer are formed on a back-side electrode, a transparent electrode is provided thereon, and the top and bottom thereof are covered with a hygroscopic film. The light-emitting layer is printed by means of screen printing or the like (see, for example, Patent Document 1). However, such a technique requires a lot of manufacturing processes. For that reason, as a method capable of achieving mass production, there is known a method of inexpensively manufacturing an inorganic EL element by means of roll printing and lamination (see, for example, Patent Document 2).